The problem of the authentication of an object, of a document or of a person is an old problem and has been the source of numerous more or less efficient solutions.
Whatever the means implemented, the methods used always have the objective of checking that the object, the document, or its bearer, which is identified is indeed authentic, and is not a copy or an illegitimate bearer.
Some known methods use an authenticating element reproduced identically over a family of products to be able to be recognized by a simple examination, for example a hologram added to the object to be checked. By the very fact of their reproduction many times identically, the checking device and method leaves some doubt as to the authenticity of the product bearing the hologram which may have been reproduced identically on non-legal products.
To resolve this difficulty, it is known practice, in particular from the patent EP 1578268, to mark each object or document, whose authenticity has to be able to be proven, by means of a non-reproducible unique authenticating element associated with an identifier element.
A unique authenticating element is an element which not only exists only in a single copy but which also cannot be reproduced identically or at least can be reproduced identically only with great difficulty or with costs exceeding the benefits that a malicious person could hope for from a reproduction of this unique authenticating element.
As is known, a unique authenticating element is obtained by a random process of scattering elements, for example bubbles in the volume of a transparent polymer, and it is not reproducible when the only means of obtaining a similar result is precisely the random process.
This case is exactly that of bubble codes.
An identifying element is more often than not a code assumed to identify a product, by a category number or part number (P/N), associated or not with a serial number (S/N).
It is thus known that a manufacturer of products has a database of its identifiers with which it associates characteristics of the authenticating element. A person wanting to check the authenticity of a product is then able to connect to the database to check the consistency of the identifier-authenticator pair for the object that he or she holds with that of the database.
A drawback of this checking method stems from the need to manage databases for each category of objects, management processes that are handled by users who apply the authenticating elements, for example labels incorporating three-dimensional bubble codes, and can lead different users to use a same identifier, for example an alphanumeric code, unique to each of them, and which will be associated with different authenticators.
When the products are unrelated to one another, the consequences seem negligible in terms of security.
When the products belong to a same category, a risk of confusion could arise, whether by chance or by design.
Such a risk seems all the more probable when the authenticating elements are standardized and likely to be produced in large numbers by one or more manufacturers such as, for example, the authenticating elements comprising colored fibers in a substrate.